New Species Of Jurassic 'Squirrels' Push Origin Of Mammals Back By 40 Million Years

Scientists have identified three new species of prehistoric squirrel-like mammals known as haramiyids that lived in China during the Jurassic period. The long-extinct species, which were about the size of mice but had long tails and feet suited for tree-dwelling, are some of the oldest mammals ever found, and their discovery pushes the timeline of mammalian evolution back by about 40 million years, according to a study published online Tuesday in the journal Nature.